Method of manufacturing a jacketed spaced-wall accumulator



y Em A. A. JACOBELLIS 3,331,1i7

METHOD OF MANUFACTURING A JACKETED 5PACEDWALL ACCUMULATOR Original FiledJuly 14, 1964 ALDHONSE A.JACOBELL\S amp/vo s United States Patent3,331,117 METHOD 0F MANUFAfiTWING A JACKETED SPACED-WALL ACCUMULATORiphonse A. .lacoheliis, 7 New Dorp Fiace,

Huntington Station, NY. 11746 Continuation of application Ser. No.382,571, July 14, 1964. This application Apr. 4, 1966, Ser. No. 540,1032 Claims. (Cl. 29-157) This invention relates in general to a method ofmanufacturing piston type pressure accumulators and more particularly toa method of manufacturing a jacketed accumulator.

This application is a continuation of application Ser. No. 382,571 filedJuly 14, 1964, now abandoned, and entitled, Piston Accumulator andMethod of Manufacture, which is a continuation-in-part of my co-pendingapplication, Ser, No. 214,746 filed on Aug. 3, 1962, now abandoned, andentitled, Piston Accumulator. The jacketed piston accumulator is one inwhich the gas chamber is in communication with an annular chamber thatsurrounds the main cylinder. By this means, the volume of the gaschamber is greatly increased without increasing the overall length ofthe accumulator. Thus for a given capacity a shorter accumulator may bedesigned. In many applications, such as in mobile equipment, there areequipment limitations on the length of the accumulator that may beemployed. A jacketed accumulator provides the advantage of permitting agreater capacity than could otherwise be obtained Where these lengthlimitations obtain.

The jacketed accumulator poses a serious fabrication problem. The insideof the inner cylinder must be honed to very close tolerances so that aclose fit between the piston and cylinder may be obtained and leakageavoided. The annular jacket around the inner cylinder must be Welded tothe inner cylinder in order to seal off the jacket from the atmosphere.The heat generated by the welding operation causes a distortion of theinner cylinder and thus would undo the close tolerances obtained duringhoning. Accordingly, the inner cylinder must be honed after the jackethas been welded to the inner cylinder. But, if the jacket has beenwelded to the inner cylinder prior to the honing, the end piece sectionof the jacket creates a dead end at the gas chamber end of the innercylinder (where the inner cylinder communicates with the chamber definedby the jacket and outer surface of the inner cylinder). Because of thisdead end, the subsequent honing step becomes very difficult andexpensive since it is not possible to hone straight through as one wouldwith a cylinder open at both ends Accordingly, it is a major purpose ofthis invention to devise a method for manufacturing a jacketedaccumulator that will avoid the necessity of having to hone to a deadend.

In brief, the method of this invention accepts the necessity of havingto hone subsequent to welding the jacket to the inner cylinder.According to this invention, an end piece is provided for the jacketwhich can be welded to the jacket (not to the inner cylinder) after thehoning operation. Thus the jacket may be welded to the inner cylinder.without the jacket end piece being attached so that the inner cylinderis open at both ends. The inner cylinder is then honed all the waythrough. The end piece is then welded to the jacket and, because it iswelded to 7 3,331,111 Patented July 18, 1357 the jacket, is Welded at aposition sufiiciently removed from the inner cylinder so that the heatof the welding does not cause the inner cylinder to distort or go out ofround.

Other purposes and objects of this invention will be apparent from thefollowing drawings and detailed descriptions, in which: I

FIG. 1 is a cross-sectional view along the main axis of the accumulatorof this invention;

FIG. 2 illustrates the intermediate product after a first step inassembling the accumulator of FIG. 1;

FIG. 3 illustrates an intermediate product after a second assembly step;

FIG. 4 illustrates an intermediate product after a third assembly step;and

FIG. 5 is an exploded view just prior to the last assembly step whichprovides the product of FIG. 1.

With reference to FIG. 1, the accumulator 10 of this invention has aninner cylinder 12 which has been honed to close tolerances so that apiston 14 will ride within the cylinder 12 and maintain an effectiveseal between the gas chamber 16 and oil chamber 18. Various O-rings 20and Teflon sealing rings 22 perform the function of sealing the twochambers 16 and 18 from each other while permitting the piston 14 toride along the cylinder 12 in response to pressure on the piston 14.

A conventional end cap 24 is illustrated at the end of the liquidchamber 18. The end cap 24 is fastened to the cylinder 12 byconventional fastening means. An opening 21 in the end cap 24 permitscommunication between the liquid chamber 18 and the outside of theaccumulator 10. Normally the opening 26 is fastened to a connection to aline carrying liquid under pressure and the liquid under pressure thusbacks into the liquid chamber 18 to supply the pressure on one face ofthe piston 14.

The gas chamber 16 is the main gas chamber in that it communicates to asecondary gas chamber 28, which secondary gas chamber 28 is formed bythe space between the jacket 30 and the inner cylinder 12. The jacket 30is a bowl-shaped member which is welded at its front end along line 32to the cylinder 12.

The jacket 30 is formed of two pieces which are welded together as oneof the last steps in the fabrication of the accumulator 10 of thisinvention. These two main jacket sections 3% are the cylindrical section300 and the rear section 3012. The rear section 3012 is welded to thecylindrical section 30a along the line 34. It is essential to themanufacture of an economical jacketed piston accumulator that the rearsection 30b and the wall section 30:: be separate sections which arewelded together during fabrication.

For ease of assembly and fabrication, the jacket 30 has a front wall 300which is welded during fabrication to the cylindrical section 30a but itis not essential to this invention that the front wall 30c Wasoriginally separate from the cylindrical wall 313a.

Small L-shaped supports 36 position the inner cylinder 12 Within thejacket 30. At least three supports 36 must be used. The one-eighth inchor so of spacing between the end of the inner cylinder 12 and the endcap 24 that is created by the support 36 is suflicient to establishcommunication between the main gas chamber 16 and the secondary gaschamber 28.

Seals 40 and 42 of a conventional sort, are illustrated in the rear capsection 30b. These seals 40, 42 are to provide a safety valve and alsoto permit opening ports in the rear cap section 30b for the purpose ofmaintenance and cleaning. These seals 40, 42 are conventional in natureand are illustrated here solely to provide a complete embodiment of theinvention.

The jacketed accumulator just described permits the method offabrication of this invention to be employed. During construction, theplate portion 300 is welded to the inner cylinder 12 along the line 32to provide the intermediate product illustrated in FIG. 2. The next stepin fabrication involves welding the cylindrical portion 30a of thejacket 30 to the plate portion 300 to produce the intermediate productillustrated in FIG. 3.

At this point in the fabrication, the inner cylinder 12 is completelyopen at both ends. Thus, the next step in fabrication is to hone theinside wall of the cylinder 12 to the desired accurate dimension andsmoothness. A stone honing device 45, as illustrated in FIG. 4, may beemployed during this step of fabrication. Because the cylinder 12 isopen at both ends, the honing can be made straight through and there isno problem of honing to a dead end.

After the inner cylinder 12 has been honed, the jacket end cap 30b ispositioned on the inner cylinder 12 and outer cylinder 30a. The jacketend cap 30b has previously had the L-shaped supports 36 Welded to it sothat the supports 36 will engage the cylinder 12 and assist in thispositioning. The jacket end cap 30b is then welded along the line 34 tothe outer cylinder 30a thus completing the fabrication steps whichconstitute the subject matter of this invention.

Further fabricating steps are necessary to complete the entireaccumulator 10 and these steps include assembling the piston 14 with itsO-rings and seals 22 inside inner cylinder 12. The end cap 24 must alsobe assembled in place as well as must be seals 40 and 42.

The sequence of fabricating steps may be varied somewhat depending uponmanufacturing convenience. Thus the welding of the jacket cylinderportion 30:: to the front plate portion 30c may precede the welding ofthe front plate portion 300 to the inner cylinder 12. However, what iessential to the method of this invention is that the welding along theline 32 precede the honing and that the jacket end cap 30b be weldedinto place after the honing.

The invention has Ibeen described in connection with the details of aspecific embodiment. Thus there are many variations in the embodimentwhich may be employed by one skilled in this art without departing fromthe scope of the invention. It is to be understood that the followingclaims are to be given a scope commensurate with the invention.

the

For example, the jacket portions 30a and 300 may be fabricated as asingle integral piece which is welded to the inner cylinder 12 prior tohoning.

What is claimed is:

1. The method of manufacturing a jacketed spacedwall accumulatorcomprising the steps of:

(a) Welding the front end of a cylindrical jacket section to the outerwall of an inner cylinder to form an annular chamber between saidcylindrical jacket section and said inner cylinder,

(13) then honing through the entire inner surface of said innercylinder, and

(c) subsequently welding a rear cap to the rear end of said cylindricaljacket section at a location spaced from said inner cylinder,

whereby the heat of said welding of said rear cap to said cylindricaljacket section will not be directly applied to said inner cylinder andthus will be insufficient to cause a distortion of the honed innersurface of said inner cylinder.

2. The method of manufacturing a jacketed spacedwall accumulatorcomprising the steps of:

(a) Welding the front end of -a cylindrical jacket section to the outerwall of an inner cylinder to form an annular chamber between saidcylindrical section and said inner cylinder,

(b) then honing through the entire inner surface of said inner cylinder,and

(c) subsequently welding a rear cap to the rear end of said cylindricaljacket section at a location spaced from said inner cylinder, said rearcap Ibeing spaced from the rear end of said inner cylinder to providecommunication between said annular chamber and the interior of saidinner cylinder,

whereby the heat of said welding of said rear cap to said cylindricaljacket section will not be directly applied to said inner cylinder andthus will be insufficient to cause a distortion of the honed innersurface of said inner cylinder.

References Cited UNITED STATES PATENTS 1,629,427 5/1927 Whitworth 29-445 1,808,442 6/ 1931 Weide. 2,216,987 10/1940 Rose 29--156.4 2,417,8733/1947 Huber 138-31 2,560,023 7/ 1951 Workman 29-445 X 2,703,108 3/1955McCuistion 13831 2,775,255 12/1956 Snyder 13831 X 3,001,268 9/1961 Greer29-157 FOREIGN PATENTS 956,394 8/ 1949 France.

CHARLIE T. MOON, Primary Examiner.

1. THE METHOD OF MANUFACTURING A JACKETED SPACEDWALL ACCUMULATORCOMPRISING THE STEPS OF: (A) WELDING THE FRONT END OF A CYLINDRICALJACKET SECTION TO THE OUTER WALL OF AN INNER CYLINDER TO FORM AN ANNULARCHAMBER BETWEEN SAID CYLINDRICAL JACKET SECTION AND SAID INNER CYLINDER,(B) THEN HONING THROUGH THE ENTIRE INNER SURFACE OF SAID INNER CYLINDER,AND (C) SUBSEQUENTLY WELDING A REAR CAP TO THE REAR END OF SAIDCYLINDRICAL JACKET SECTION AT A LOCATION SPACED FROM SAID INNERCYLINDER, WHEREBY THE HEAT OF SAID WELDING OF SAID REAR CAP TO SAIDCYLINDRICAL JACKET SECTION WILL NOT BE DIRECTLY APPLIED TO SAID INNERCYLINDER AND THUS WILL BE INSUFFICIENT TO CAUSE A DISTORTION OF THEHONED INNER SURFACE OF SAID INNER CYLINDER.